lib: Fix 32-bit sparc udiv_qrnnd() definition in mpilib's longlong.h
David Miller [Wed, 1 Feb 2012 22:17:55 +0000 (00:17 +0200)]
This copy of longlong.h is extremely dated and results in compile
errors on sparc32 when MPILIB is enabled, copy over the more uptodate
implementation from arch/sparc/math/sfp-util_32.h

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: James Morris <jmorris@namei.org>

lib/mpi/longlong.h

index b87487b..29f9862 100644 (file)
@@ -1200,18 +1200,40 @@ do { \
        "r" ((USItype)(v)) \
        : "%g1", "%g2" __AND_CLOBBER_CC)
 #define UMUL_TIME 39           /* 39 instructions */
-#endif
-#ifndef udiv_qrnnd
-#ifndef LONGLONG_STANDALONE
+/* It's quite necessary to add this much assembler for the sparc.
+   The default udiv_qrnnd (in C) is more than 10 times slower!  */
 #define udiv_qrnnd(q, r, n1, n0, d) \
-do { USItype __r; \
-       (q) = __udiv_qrnnd(&__r, (n1), (n0), (d)); \
-       (r) = __r; \
-} while (0)
-       extern USItype __udiv_qrnnd();
-#define UDIV_TIME 140
-#endif /* LONGLONG_STANDALONE */
-#endif /* udiv_qrnnd */
+  __asm__ ("! Inlined udiv_qrnnd\n\t"                                  \
+          "mov 32,%%g1\n\t"                                            \
+          "subcc       %1,%2,%%g0\n\t"                                 \
+          "1:  bcs     5f\n\t"                                         \
+          "addxcc %0,%0,%0     ! shift n1n0 and a q-bit in lsb\n\t"    \
+          "sub %1,%2,%1        ! this kills msb of n\n\t"              \
+          "addx        %1,%1,%1        ! so this can't give carry\n\t" \
+          "subcc       %%g1,1,%%g1\n\t"                                \
+          "2:  bne     1b\n\t"                                         \
+          "subcc       %1,%2,%%g0\n\t"                                 \
+          "bcs 3f\n\t"                                                 \
+          "addxcc %0,%0,%0     ! shift n1n0 and a q-bit in lsb\n\t"    \
+          "b           3f\n\t"                                         \
+          "sub %1,%2,%1        ! this kills msb of n\n\t"              \
+          "4:  sub     %1,%2,%1\n\t"                                   \
+          "5:  addxcc  %1,%1,%1\n\t"                                   \
+          "bcc 2b\n\t"                                                 \
+          "subcc       %%g1,1,%%g1\n\t"                                \
+          "! Got carry from n.  Subtract next step to cancel this carry.\n\t" \
+          "bne 4b\n\t"                                                 \
+          "addcc       %0,%0,%0        ! shift n1n0 and a 0-bit in lsb\n\t" \
+          "sub %1,%2,%1\n\t"                                           \
+          "3:  xnor    %0,0,%0\n\t"                                    \
+          "! End of inline udiv_qrnnd\n"                               \
+          : "=&r" ((USItype)(q)),                                      \
+            "=&r" ((USItype)(r))                                       \
+          : "r" ((USItype)(d)),                                        \
+            "1" ((USItype)(n1)),                                       \
+            "0" ((USItype)(n0)) : "%g1", "cc")
+#define UDIV_TIME (3+7*32)      /* 7 instructions/iteration. 32 iterations.  */
+#endif
 #endif /* __sparc__ */
 
 /***************************************